Methane distribution surrounding closed landfill sites in China

Area of Science:

• Environmental Science
• Geochemistry
• Atmospheric Chemistry

Background:

• Landfills are significant sources of atmospheric methane, a potent greenhouse gas.
• Methane release occurs through landfill gas emissions and dissolved methane in surrounding water bodies.
• Understanding methane distribution is crucial for assessing environmental impact and developing mitigation strategies.

Purpose of the Study:

• To investigate methane distribution in leachate, groundwater, and surface air around a closed landfill.
• To analyze the influence of redox species within the leachate plume on methane distribution.
• To quantify methane emission levels and their persistence over time.

Main Methods:

• Field sampling of leachate, groundwater, and surface air.
• Chemical analysis for methane and redox species (e.g., sulfate).
• Spatial mapping of methane concentrations around the Erfei Shan landfill.

Main Results:

• High dissolved methane concentrations detected in raw leachate (up to 46.07 mg L(-1)) and shallow groundwater (up to 27.95 mg L(-1)).
• Methane depletion observed in areas with elevated sulfate concentrations (7-10 m depth).
• Variable surface air methane concentrations (average 14.01–118.29 mg L(-1)) linked to emission sources.

Conclusions:

• Methane release from closed landfills is a long-term environmental concern.
• Redox conditions, particularly sulfate presence, influence methane distribution in subsurface environments.
• Surface methane levels indicate ongoing, albeit potentially low-level, emissions from the closed landfill.